Bob,
The hardest part is getting the alignment onto the two large bolts protruding from the lower frame. The second challenge is getting the two bolts into the frame started.
I can't remember if the 1641 has nuts to accept bolts or if you need to get a nut behind the frame to attach it.
I've used a 4x4 under the frame of the blower to get it at about the right height, and then drive slowly into it.
It's not hard, but it does test your patience.
Once it's on, you can thread the belt around the PTO, through the two idlers on the blower and just roll it onto the blower geabox pulley.
Good luck.
Curt